Dallas smog, seen here on a bad day, is a health risk, but whose job is it to clean it up?

Texas’ top pollution regulators will hear an argument tomorrow that almost certainly will fail. But it might kick off some discussion on global warming, public health and North Texas smog.

Jed Anderson is a Houston lawyer whose clients include companies that emit pollution. He will tell the state that harmful emissions from elsewhere worsen Texas’ air quality, so industries in Texas shouldn’t have to make extra efforts to compensate for them.

Anderson will ask the three commissioners of the Texas Commission on Environmental Quality, meeting in Austin, to use a loophole in federal law to avoid new restrictions on Texas industries if global warming boosts local air pollution.

The agency’s executive director says the commissioners should tell Anderson no, calling his analysis “superficial” and scientifically weak. A recommendation for denial usually dooms such requests.

Anderson’s case in point is the human contribution to global warming from power plants, refineries, vehicles and a wide range of other sources. Texas has an outsized share of U.S. emissions, due to its size and heavy industrial base.

But on a global scale, Anderson argues, Texas pollution is an insignificant blip (a statement that by itself would kick off all sorts of fights).

At that point his case gets more complicated. Since lung-damaging ozone forms in hot weather, some studies suggest that higher average temperatures from global warming could boost ozone levels in urban areas such as Dallas-Fort Worth and Houston.

More smog means tighter controls on the local sources of ozone-forming emissions. But if greenhouse-gas emissions in China or India are worsening ozone in Dallas or Houston, Anderson asks, why should local companies bear the extra burden?

“I just don’t think the best way for addressing foreign pollution is to wait until it blows over here and then require Texan citizens to offset this foreign pollution, in addition to reducing their own pollution impacts, by installing additional controls on Texas citizens and businesses,” Anderson told The Dallas Morning News in an email.

“I believe that if the state stopped accepting responsibility for pollution they can’t control (e.g. foreign pollution), [then] the federal government, who has the constitutional authority to control it, would be put more in a position to have to do something about it.”

Anderson wants the TCEQ to invoke a seldom-used provision of the federal Clean Air Act that gives urban areas some leeway if another country’s pollution blows in and worsens local air quality.

The classic case is El Paso, where emissions from Juárez, Mexico are a big local factor. The loophole isn’t typically used to blame countries half a world away.

The Environmental Protection Agency hasn’t commented on Anderson’s idea, but in a report last month it said scientific understanding of how global emissions affect local conditions is too uncertain at this point to rely on for local pollution decisions.

Foreign emissions are important to U.S. air quality, the EPA said, but aren’t expected to be a key factor for most cities.

TCEQ Executive Director Richard A. Hyde, in his recommendation for denial of Anderson’s request, called Anderson’s analysis of scientific papers “superficial” and said he had cited research “uncritically.” Hyde also agreed with the EPA that the link between global emissions and local smog is too tenuous at the moment.

Public-health advocates say in talking about local ozone it’s vital to remember the real purpose of local rules: to protect local people. A Dallas child’s asthma attack, they note, is dangerous no matter where the airborne gunk comes from.

Many researchers say there are obvious links between global warming and human health, from the spread of tropical disease to heat stress. The potential impact of a disrupted climate on human health was the main factor that led the EPA to regulate greenhouse-gas emissions under the Clean Air Act.

Texas, some other states, industries and the Obama administration’s congressional critics blasted that decision as illegal, but the Supreme Court has upheld it twice.

Anderson’s plan also could stir complaints that it’s just a gift to Texas polluters. It’s true that no one power plant or refinery is responsible for global warming. Neither is any one car the cause of North Texas smog, nor is one litterer the source of trash across Texas.

But the law still applies to each.

Anderson said it’s just a matter of who should pay for solving the problem.

“The issue, I think, is who is in the best to most cost-effectively address foreign pollution,” he said. “I believe it is the federal government and not the states.”

Health officials urge the public to take protective measures by utilizing the ‘4Ds’ to reduce the risk of West Nile virus:

DEET All Day, Every Day: Whenever you’re outside, use insect repellants that contain DEET, picaridin or oil of lemon eucalyptus.DRESS: Wear long, loose and light-colored clothing outside.DRAIN: Remove all areas of standing water in and around your home.DUSK & DAWN: Limit outdoor activities during dusk and dawn hours when mosquitoes are most active.

The types of mosquitoes that can spread chikungunya are common in Texas.

It was just a matter of time.

Given the heavy travel patterns to Caribbean countries where the new mosquito-born virus is spreading widely, it was inevitable that someone would bring it back to Dallas County.

Dallas County Health and Human Services confirmed Tuesday the first case of imported Chikungunya virus in Dallas County this year.

The patient was infected with the virus during recent travel to the Caribbean, and was diagnosed after returning home, the health department said. For medical confidentiality and personal privacy reasons, the county does not provide additional identifying information.

In a related case, Joel Peralta, a relief pitcher for the Rays says he believes he has chikungunya, according to CBS Sports.com. Peralta returned to his native country, the Dominican Republic, over the All-Star break and told MLB.com that he believes he was bitten by a mosquito “one or two times.” He has been placed on the disabled list.

The virus causes high fever and severe joint pain that start suddenly. It can also cause headache, muscle pain and rash. Chikungunya does not often result in death, but the symptoms can be disabling, and some people suffer severe complications. There is no specific medication available to treat the virus and there is not a vaccine. Avoiding mosquito bites is the key to avoid getting infected.

The virus spreads only if someone in the infectious stage of the disease is bitten by a mosquito, which later bites someone else. Usually, anyone infected with the virus is stays away from other people during the early part of the illness.

The county health department advises the public to use the ’4Ds’ to help reduce the chance of being bitten by a mosquito infected with Chikungunya or the West Nile virus. They include:

Almost daily, a new mosquito pool in Dallas County is testing positive for the West Nile virus.

On Monday, the first ZIP code in the city of Dallas (75230) had positive mosquitoes, followed by a positive pool in Carrollton (75007) on Tuesday and another in a Dallas ZIP code (75240) on Wednesday.

Each positive pool triggers night-time spraying of insecticides within a half-mile radius by city or county crews. Residents of the affected areas are notified of the spraying schedules and urged to stay indoors when the sprayers are out.

So far, there have been no confirmed cases of human infections locally by the mosquito-borne virus, which makes an annual return to North Texas from April through October.

The virus causes no symptoms in most people who are bitten, while headaches, fevers and aches will occur in about 20 percent. About 1 in 150 people will suffer severe neurological symptoms, such as meningitis, encephalitis or a polio-like paralysis.

Although mosquitoes have tested positive for the West Nile virus in a handful of suburban communities this year, local health officials are hoping for a mild season with few human infections.

“It appears to be a slow start,” Zachary Thompson, director of Dallas County Health and Human Services, said Friday.

“But in past years, we’ve seen slow starts and then a surge of cases in July,” he recalled of the mosquito-borne virus, which first appeared in North Texas in 2002.

As of this week, no West Nile infections had been reported in local residents. As of June 14, the county has tested 1,834 mosquito pools and found none contained insects carrying West Nile.

However, independent labs that perform tests in some Dallas County cities found infected mosquitos in ZIP codes 75137 in Duncanville, 75104 in Cedar Hill, 75019 in Coppell and 75038 in Irving.

A mosquito pool in Tarrant County’s Benbrook — ZIP code 76116 — also tested positive for the virus this week, according to Tarrant’s public health department.

Each positive report is followed by pesticide spraying within a half-mile radius of the infected trap. This year, local cities and counties are committed to spraying within 24 hours of a positive test result or confirmed human infection. Some are hoping for an even faster turnaround.

Remember the four Ds:

DRAIN standing water in your yard and neighborhood. Standing water can be found in swimming pools that are not kept clean, ponds, pet watering dishes, birdbaths, potted plants, old tires, empty containers, toys and clogged rain gutters.

DUSK/DAWN are the times of day you should stay indoors when mosquitoes are most active.

DRESS in long-sleeved shirts and wear pants when you are outside. Spray thin clothing with insect repellent.

DEET is an ingredient to look for in your insect repellent (or use an organic alternative such as orange spray, eucalyptus or citronella).

Dallas County's health department was frequently inundated with people needing vaccinations due to year-round disease outbreaks.

Infectious diseases were not kind to Dallas County in 2013.

As final tallies are being released this month by Dallas County Health and Human Services, it is clear that viruses almost took turns hitting specific age groups last year.

A record number of children were stricken by whooping cough. The elderly were targeted by the West Nile virus, although many fewer than in 2012. And young to middle-aged adults suffered from an unusually deadly flu season.

The county’s epidemiology staff was kept busy practically every day last year tracking illnesses that might have been prevented.

Perhaps the surprise outbreak was pertussis or whooping cough. Last year, Dallas County had a 55 percent increase in reported cases compared to 2012.

The 401 cases also appeared to be the highest number since the county began tracking the disease in 1952. Most of last year’s cases — 84 percent — occurred in infants and children under 18 years of age. Hispanic and white children were hit the hardest.

Of the 39 children hospitalized with whooping cough, 74 percent were less then a year old. But of those who were stricken, 84 percent had received one or more shots of the pertussis vaccine.

Public health officials, including the Centers for Disease Control and Prevention, are blaming the outbreak on a weak vaccine and the failure to get timely booster shots. Pertussis requires about a half dozen shots to protect adults and children.

While there is no vaccine for West Nile, Dallas County and its various cities are proactive about preventing infections. Every spring brings an annual education campaign in hopes of thwarting the mosquito-borne virus.

Residents are reminded to use insect repellant when outdoors from May through November, and to wear long pants and shirts outside at dawn and dusk when mosquitoes are active. Standing water also should be emptied to eliminate mosquito breeding sites.

Last year’s outbreak was a marked improvement over 2012 when Dallas County was the epicenter of the nation for the West Nile virus. Twenty deaths and more than 400 human infections were counted two years ago.

The final report for 2013 confirmed 11 West Nile infections and two deaths. The median age of those infected was 53 with the range from 7 to 81 years old. However, 64 percent of the cases were adults 50 years or older.

The annual flu outbreak, which began last fall, is continuing into March, with 51 adult deaths counted as of last week. However, the latest flu-related fatality was an 8-year-old reported this week by a local hospital.

Nearly 6,000 county residents have been stricken by the flu, according to lab tests so far this season. More than 1,000 people required hospitalization, many of them in intensive care.

Officials are blaming the H1N1 virus or swine flu, which last struck North Texas in 2009-2010. The virus is hitting hardest among a younger demographic than is typical for the flu.

Usually, it is the elderly who struggle with severe flu complications, often related to their underlying health problems. But this season, the median age for illness was 49 years.

Younger adults probably were not exposed to earlier versions of the virus and have not taken the opportunity to get vaccinated in the past five years, officials theorize.

The county’s weekly flu report is always accompanied by a public advisory to get a flu shot. The county’s flu vaccine remained available throughout the deadly season.

Dallas County Health and Human Services announced Monday the fourth West Nile human infection of the season.

The victim was a man over 60 who lives in ZIP code 75224 in central Oak Cliff, an area that straddles I-35. He suffered severe neuroinvasive symptoms, said Zachary Thompson, director of the health department.

County officials continued to urge residents to use insect repellent when outdoors and to wear long pants and sleeves when going outside at dusk and dawn when mosquitoes are active.

West Nile is a virus carried in birds that can spread to people by mosquitoes that feed on birds and humans.

“The first line of defense to prevent West Nile virus infection is to avoid getting bitten in the first place,” he said.

Such measures also include removing outdoor standing water, where mosquitoes can breed. Windows and doors also should be mosquito-proofed to keep the insects out of the house.

Since April, Dallas County has found 89 mosquito pools that were positive for West Nile. Northeast Dallas County appears to have more infected pools than in other areas.

The three previous human cases were in Grand Prairie, Richardson and University Park.

West Nile causes no symptoms in about 80 percent of the people who become infected. About 20 percent will develop a mild headache, fever and chills. About 1 in 150 of those infected will suffer more severe neuroinvasive symptoms, including meningitis, encephalitis and a polio-like paralysis.

This year’s West Nile season is a far cry from what happened last year, when Dallas County was the nation’s hot spot for the virus. More than 400 residents developed mild to severe West Nile symptoms and 20 died from virus-related illnesses.

The massive outbreak caused Dallas County to launch an aerial attack against the disease-carrying mosquitoes exactly a year ago. It was the first time in nearly 60 years that the county restorted to aerial spraying of insecticides in hopes of ending a disease outbreak.

County officials declared the effort successful when the number of human infections declined in the following weeks. Early this year, the Centers for Disease Control and Prevention confirmed that those areas that had been sprayed from the air saw a greater decline in West Nile cases compared to areas that did not receive it.

Compared to 2012, mosquito abatement has been more aggreesive this year, particularly in Dallas and other surrounding counties that were hard hit by West Nile last year.

City and county mosquito-control efforts are not waiting until mosquitoes test positive for the virus to begin spraying. Truck-mounted sprayers are being sent out whenever mosquito-pool surveillance detects large numbers of Culex mosquitoes capable of carrying West Nile.

Zachary Thompson was trying to say something positive about West Nile at his weekly briefing Tuesday for Dallas County commissioners.

By this time last year, 103 mosquito traps had tested positive for the mosquito-borne virus and nine human infections had been confirmed, said the director of Dallas County Health and Humamn Services.

“The fact we have no human West Nile cases to date [this year] is a good sign,” he told the commissioners. “The data speaks for itself.”

So far this summer, the county’s mosquito surveillance program has detected no mosquitoes carrying West Nile. However, other mosquito labs operating in the county have detected the virus in seven mosquito pools since mid-April.

The infected pools were found in ZIP codes 75217 and 75208 in Dallas,
75205 in Highland Park, and 75080 and 75081 in Richardson. (To follow the 2013 outbreak click on the West Nile Watch page updated at least weekly by the county health staff.)

The virus is here but it’s a far cry from what happened here last summer, noted Thompson, whose staff has tracked West Nile since it first appeared in North Texas in 2002.

In 2012, about 400 Dallas County residents suffered mild to severe West Nile infections and 20 people died from complications of the virus. It was the worst outbreak in county history and the hardest hit spot in the nation last year, according to the Centers for Disease Control and Prevention.

“We thank God we are not having a similar outbreak as last year,” Thompson said.

The virus causes no symptoms in about 80 percent of the people who become infected, but can cause fever, headache and chills in about 20 percent. In one out of 150 infections, a person will develop severe illness, including meningitis, encephalitis and polio-like paralysis.

Thompson gave credit to local mosquito abatement efforts, which has responded with ground spraying of insecticide whenever the virus shows up as well as whenever large pools of Culex mosquitoes are found. This is the type capable of carrying West Nile, a bird virus that spreads to people via mosquitoes.

He also thanked anyone who is taking West Nile precautions by using insect repellent and wearing long sleeves and pants outdoors at dawn and dusk when mosquitoes typically feed.

Finally, the health department director also gave special credit to Dr. Christopher Perkins, the county’s medical director, who is tracking mosquito abatement efforts and urging safety precautions.

However, it was too soon to breath a sigh of relief given that the virus can spread as late as November.

“We’ve still got a long way to go in terms of this season,” Thompson warned.

When West Nile swept into North Texas last summer, the first sign of trouble showed up in the local blood supply.

On June 5, 2012, a local blood donor tested positive for the mosquito-borne virus. It was the first time in three years that the virus had appeared in donated blood.

So far this year, West Nile testing of blood donations has turned up nothing.

“It is good news for our territory,” said Yesenia Olive, spokeswoman for Carter Bloodcare, the largest blood bank in North Texas. It covers a 58-county area in East, Central and North Texas.

As June slips away, only one positive human West Nile infection has been confirmed in the Dallas area. The June 14th case involved a Fort Worth woman who suffered the less severe form of the disease.

The relative quiet of this summer is a stark contrast to what happened in 2012.

All last summer, as hundreds of West Nile cases and dozens of deaths were being confirmed by local public health officials in North Texas, blood banks were also turing up asymptomatic cases and notifying health authorities.

In all, 72 Carter blood donations tested positive for West Nile, a record that was mirrored by the active cases of the disease confirmed in Tarrant, Dallas, Collin and Denton counties.

Blood donations offer a unique perspective on how the West Nile virus is spreading.

Positive test results represent the silent cases of the disease that are spreading in a community. As they pop up, health officials can track where the disease is spreading, providing insight into the unseen side of the epidemic.

The virus, which is harbored in birds, can spread to people by mosquitoes that feed on both birds and humans.

Since roughly 80 percent of the people who are infected by West Nile show no symptoms, they do not know they have an active infection.

The 20 percent who suffer mild, flu-like aches, headaches and fever might go to the doctor if they feel sick enough. But most of them aren’t tested either.

The infections that are the most noticable are the ones who suffer severe illness — one in 150 who are infected — and develop meningitis, encephalitis and a polio-like paralysis. Usually, they require hospital care and some of them die.

The high infection level in the blood supply allowed local health officials to estimate the size of the four-county West Nile outbreak by taking into account these silent cases.

Carter’s positive tests resulted in an estimate that more than 80,000 residents in the four hardest-hit counties had become infected with West Nile.

Blood donors who tested positive for an active infection were notified of the results and their blood donation was not used. In a few cases, some donors showed symptoms of a West Nile infection after they gave blood.

Blood banks have been screening donations for West Nile since 2003, four years after the virus first appeared in the United States. It reached Texas in 2002.

While the summer has been quiet here so far, local health departmemnts are spraying insecticide as a preemptive measure, based on the presence of mosquitoes capable of carrying West Nile. Five positive mosquito pools in Dallas County so far this year have not resulted in human infections.

But the end of West Nile season is a long ways away.

Carter’s final West Nile infection was confirmed last Oct. 22. Dallas County confirmed its final severe case of the neuroinvasive disease in late November.